Seedling containers are available which comprise a styrofoam block provided with a plurality of cone-shaped cavities therein for the tree seedlings.
In use, seeds, together with a growing material, such as a compost mixture, is introduced into the cavities. When the seeds germinate and the seedlings grow, a root structure is developed in the growing material which is easily extracted from the cavity due to the conical form of the cavity. The growing material and root structure is in the form of a plug when removed from the cavity and the seedling is planted in the soil by making an appropriate hole with a dibble in the soil to receive the plug.
To give the seedling the best chance of surviving the transplanting operation, it is essential for the seedling to have a well-developed and healthy root structure. It should not become potbound, i.e. the roots should not be pot bound, i.e. spiral, and the roots should be branched out as much as possible so that the roots can spread out quickly in the ground once transplanted and take hold.
In order to promote branching, chemical treatment methods have been employed, such as treating the cavities in which the seedlings are grown with a copper carbonate solution. This is intended to stop root growth where contact with the copper compound is made and thus cause side roots to form. However, this method has the disadvantages that the ends of the roots are chemically burned off, thus defeating the purpose of producing a healthy natural root, and further, the seedlings treated in this way are susceptible to copper imbalances.